The invention relates to a toothed power transmission belt, but more particularly, the invention relates to a fabric reinforcement associated with the teeth of such a belt.
Power transmission belts have a polymeric body with a plurality of teeth along at least one surface of the belt. Many such belts have a tensile member embedded in the body as a load carrying member, and a wear resistant fabric at the periphery of the surface that includes the belt teeth for reinforcing such teeth and inhibiting wear. The type of wear resistant fabric has an impact on the load carrying capacity of the belt teeth, and consequently, the belt itself.
U.S. Pat. No. 3,937,094 and U.S. Pat. No. 4,099,422 each disclose a toothed power transmission belt with trapezoidal belt teeth. The peripheral surface of the belt including the teeth, have two layers of fabric which provide a wear resistant surface to the teeth and structural reinforcement to the teeth. A problem during belt use with such a construction, is delamination of the two layers of fabric which are adhered together such as by means of a cement or a rubber layer. Another problem associated with the construction is that the two layers of fabric and the adhesive mechanism to preclude the fabrics from separating from each other, are a cost penalty in the manufacture of such a belt.
U.S. Pat. No. 4,392,842 discloses a toothed power transmission belt with rounded teeth formed at a surface of the belt. There are two layers of fabric adjacent the surface that includes the belt teeth. The fabrics are separated from each other with a cushion layer of elastomeric material so as to decrease the rigidity of the belt teeth in comparison to the previously mentioned two layer fabric constructions. While such a construction may be beneficial for a rounded toothed belt, the two layers of fabric, their spacing, and adhesion system for the fabric layers adds to the manufacturing steps and costs for producing such a belt.
U.S. Pat. No. 4,302,197 discloses a toothed power transmission belt with a single layer of fabric at the peripheral surface including the belt teeth where the fabric is constructed such that its outside has fiber with properties for abrasion resistance and the inside has fiber with properties for adhesion with the polymeric body of the belt. While such a fabric construction is beneficial for abrasion resistance and adhesion properties, it does not provide the tooth reinforcement exhibited by a belt construction with two layers of fabric of the previously mentioned belts.